By "Luke", am assuming you mean from Cord Cutters News.
Anyways, he was probably referring to a RokuTV. (This is a TV with a built-in, integrated Roku OS). You can combine Antenna/OTA channels and Roku Channel Streaming channel into one guide.
A RokuTV is different than a TV with a Roku streaming device connected via HDMI. In these setups, the LiveTV guide is limited to the Roku Channel Streaming channels currently. Since these HDMI connected streaming devices do not have an antenna tuner inside of them, as opposed to a RokuTV, they cannot receive antenna/OTA signals. In order to receive antenna/OTA channels, you will need to switch to the Antenna Input on your TV (using the TV remote, not the Roku remote).
Feel free to post back with your setup (verify if you have a RokuTV or a Roku device connected via HDMI and the model number from Settings/System/About).
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941